An Interesting Conundrum

I have just been reading this super interesting article all about a psychologist’s perspective on UX design. One line that caught my attention was this:
[LIST]
[*]People prefer [B]short line lengths[/B], but they [B]read better with longer ones[/B]! It’s a conundrum, so decide whether preference or performance is more important in your case, but know that [B]people are going to ask for things that actually aren’t best for them[/B].
[/LIST] How do we get around the fact that people don’t know what they really need (or what is best for them)?

I’ve always adhered to the words of Neil Gaiman, which I’m paraphrasing here: When people tell you something is wrong, they’re almost always right. When they tell you how to fix it, they’re almost always wrong.

I would say about the only way to deal with this is A/B testing and see what gets results. I think you see symptoms of this when platform X changes feature Y, all the users on platform X promise to revolt audibly, but you see that it actually performs better. I tend to lay back on criticism of these kinds of changes like when they happen on social networks (although some of the latest Twitter changes are making me scratch my head), as I’m not working for the business and don’t have any context for why these changes are being made.